The latest Washington scandal is over ordinarily the least scandalous of men, a government actuary and his cost estimates for Medicare's new prescription drug benefit. It's generally accepted now that the new drug entitlement will cost at least $534 billion over 10 years, but last November when the final bill squeaked through the House by five votes, Thomas A. Scully, Medicare's administrator at the time, was still insisting on a $400 billion cost, an early estimate by the Congressional Budget Office. It has since come out that Richard S. Foster, Medicare's supposedly independent actuary, had pegged the cost at $551.5 billion at least as long ago as June, and Bush appointee Scully may have threatened Foster with firing if he went public about the true costs. The higher estimate could have turned wavering Republican conservatives against the bill.

Government projections are never an exact science. That's all the more reason to lay out the best estimates for lawmakers, and let the political chips fall where they may. It is one thing to spin the numbers, but altogether more damaging to suppress them.

Foster's higher estimate was circulated among some lawmakers, but two sets of numbers added to the uncertainty. Some powerful Republicans and Democrats claim they didn't know about the higher cost until after the vote and President Bush signed the bill on Dec. 8. House majority leader Tom DeLay, one of the negotiators, told the New York Times Wednesday he didn't learn about it until January when Bush's budget director put the final figure at $534 billion.

Democrats are charging Scully broke the 1997 law, which Republicans drafted to shield Medicare's actuary from political pressure and allow him to be fired only "for cause." A House Democratic aide who hounded Foster for his estimate all last year says he told her he could get fired if he released it, and Scully later told her he could fire Foster for insubordination if Foster directly defied Scully's orders. This January, aide Cybele Bjorklund received a faxed copy of Foster's $551 billion estimate, dated June 11, 2003.

This is a presidential election year, and Democrats and Republicans are working overtime to put their own spin on the Republican-backed drug bill. The Motion Picture Academy did not exhaust all the acting awards last month. But long-term entitlement costs are no comedy. Trustees for Medicare and Social Security are expected to report this week that the two programs will need twice as much money as previously estimated, and the funding gap over the next 75 years could be as high as $50 trillion. Tuesday, they also are expected to report a 75-year cost estimate for the new prescription drug benefit.

Some lawmakers claim they were in the dark about the 10-year numbers when they voted, but Federal Reserve Board Chairman Alan Greenspan has not been flying blind. He's been urging Congress not to leave trimming future benefits to the next generation. Responsible trims start with the most honest estimates actuaries can produce.